Light emitting device

ABSTRACT

Disclosed is a light emitting device. The light emitting device includes a light emitting structure comprising an active layer to generate first light, a first conductive semiconductor layer on the active layer, and a second conductive semiconductor layer on the active layer so that the active layer is disposed between the first and second conductive semiconductor layers, wherein a portion of the light emitting structure is implanted with at least one element which generates second light from the first light.

This application is a Continuation of application Ser. No. 12/642,237filed on Dec. 18, 2009 (now U.S. Pat. No. 7,977,683), which claimspriority to Application No. 10-2008-0134515 filed in the Republic ofKorea, on Dec. 26, 2008. The entire contents of all of the aboveapplications are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The embodiments of the present invention relate to a light emittingdevice (LED). The LED is a semiconductor device that converts electriccurrent into light. Since a red LED was commercialized, the red LED,together with a green LED, is used as a light source of electronicdevices which includes information communication equipment.

For example, a gallium nitride (GaN) semiconductor, which is a nitridesemiconductor, has high thermal stability and a wide bandgap. The GaNsemiconductor can be combined with other elements, such as, In and Al toform a semiconductor layer that emits green, blue and/or white lights,and wavelengths of the emitted lights can be easily adjusted, so the GaNsemiconductor has been spotlighted in the field of high-power electronicdevices, such as LEDs.

A conventional nitride semiconductor LED is formed by combining a blueLED with a fluorescent substance. The fluorescent substance absorbs apart of the blue light to emit light having a color band of green,yellow and/or red. At the present time, such a fluorescent substance haslow photoconversion efficiency and low reliability at high temperatures.Further, the fluorescent substance occupies a predetermined space on theblue LED, so a volume of the nitride semiconductor LED may be increased.

SUMMARY OF THE INVENTION

The embodiments of the present invention provide an LED capable ofimproving light emitting efficiency and diversifying application fieldsthereof.

The embodiments of the present invention provide an LED capable ofachieving a white light output and having high performance.

According to an embodiment of the present invention, a light emittingdevice includes a light emitting structure comprising an active layer togenerate first light, a first conductive semiconductor layer on theactive layer, and a second conductive semiconductor layer on the activelayer so that the active layer is disposed between the first and secondconductive semiconductor layers, wherein a portion of the light emittingstructure is implanted with at least one element which generates secondlight from the first light.

According to another embodiment of the present invention, a lightemitting device includes an active layer to generate first light; afirst conductive semiconductor layer on the active layer; a secondconductive semiconductor layer on the active layer so that the activelayer is disposed between the first and second conductive semiconductorlayers; and a conductive substrate on the first conductive semiconductorlayer, wherein a portion of the conductive substrate is implanted withat least one element which generates second light from the first light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing an LED according to a firstembodiment of the present invention;

FIGS. 2 to 5 are sectional view showing a procedure for manufacturing anLED according to an embodiment of the present invention;

FIG. 6 is a sectional view showing an LED according to a secondembodiment of the present invention;

FIGS. 7 and 8 are sectional view showing a procedure for manufacturingan LED according to another embodiment of the present invention; and

FIG. 9 is a sectional view showing an LED according to a thirdembodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an LED and a method for manufacturing the same will bedescribed with reference to the accompanying drawings.

In the description of embodiments, it will be understood that when alayer (or film) is referred to as being ‘on/over’ another layer orsubstrate, it can be directly on/over another layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being ‘under/below’ another layer,it can be directly under/below another layer, and one or moreintervening layers may also be present. In addition, it will also beunderstood that when a layer is referred to as being ‘between’ twolayers, it can be the only layer between the two layers, or one or moreintervening layers may also be present.

First Embodiment

FIG. 1 is a sectional view showing an LED according to a firstembodiment of the present invention. The LED according to the firstembodiment includes a first conductive semiconductor layer 110, anactive layer 120 and a second conductive semiconductor layer 130.Roughness R is formed at a first area of the first conductivesemiconductor layer 110, and a portion 115 having an implanted elementis in the first conductive semiconductor layer 110 having the roughnessR. Reference numerals which are not described in FIG. 1 will beexplained in the manufacturing method thereof. In embodiments of thepresent invention, the roughness R is a portion having a texturedsurface roughness. Such textured surface roughness may be at least oneprotrusion and/or at least one depression. The textured surfaceroughness may be a plurality of protrusions and depressions formed on asurface, or a portion thereof, and may have regular or irregularperiodicity, or may be formed randomly. The shapes of the protrusionsmay be spine-like, column-like, or other shapes, and the shapes of thedepressions may be indentations, channels, grooves, or other shapes.

According to the LED of the first embodiment, the implanted element maybe rare earth elements that are partially implanted into a surface ofthe first conductive semiconductor layer 110, and a first electrodelayer 150 is formed on the first conductive semiconductor layer 110 ofhigh-quality, so that degradation in crystallization of a thin filmcaused by the implantation of the rare earth elements can be reduced orprevented, degradation in performance of the LED caused by degradationof electrical properties can be effectively reduced or solved, and asingle chip white LED having high performance can be achieved. In otherembodiments, the implanted element may be other elements, such asphosphor or other doping materials that have fluorescence or are able toabsorb one light to generate another light. In a broad sense, an elementrefers to any element listed in the periodic table. It should beunderstood that light also references any radiation, as well aswavelength bands of light that are not visible to humans.

Hereinafter, the manufacturing method of the LED according to anembodiment of the present invention will be described with reference toFIGS. 2 to 5. First, as shown in FIG. 2, a first substrate 100 isprepared. The first substrate 100 may be a sapphire (Al₂O₃) singlecrystalline substrate. However, the present invention is not limitedthereto. Wet cleaning is performed relative to the first substrate 100to remove impurities on the surface of the first substrate 100.

Next, the first conductive semiconductor layer 110 can be formed overthe first substrate 100. For example, the first conductive semiconductorlayer 110 can be formed through chemical vapor deposition (CVD),molecular beam epitaxy (MBE) or hydride vapor phase epitaxy (HYPE).Further, the first conductive semiconductor layer 110 can be formed byinjecting silane gas SiH₄ containing N type impurities, such astrimethylgallium gas TMGa, ammonia gas (NH₃), nitrogen gas N₂ andsilicon Si, into a chamber containing the first substrate 100.

Then, the active layer 120 can be formed over the first conductivesemiconductor layer 110. Electrons injected through the first conductivesemiconductor layer 110 are combined with holes injected through thesecond conductive semiconductor layer 130 at the active layer 120, sothe active layer 120 emits light having predetermined energy and/orwavelength, which is determined according to an energy band of materialforming the active layer 120. The active layer 120 may have a quantumwell structure formed by alternately laminating nitride semiconductorlayers having different energy bands either once or several times. Forexample, the active layer 120 may have a multi-quantum well structurewith an InGaN/GaN structure, which is formed by injectingtrimethylgallium gas TMGa, ammonia gas NH₃, nitrogen gas N₂ andtrimethylindium gas TMIn. However, the present invention is not limitedthereto. Further, the active layer 120 may be formed at the temperatureof about 760° C. to emit blue light. However, the present invention isnot limited thereto.

Thereafter, the second conductive semiconductor layer 130 can be formedover the active layer 120. For example, the second conductivesemiconductor layer 130 can be formed by injectingbis-ethylcyclopentadienyl magnesium (EtCp₂Mg){Mg(C₂H₅C₅H₄)₂} containingP type impurities, such as trimethylgallium gas TMGa, ammonia gas NH₃,nitrogen gas N₂ and Magnesium Mg, into the chamber. However, the presentinvention is not limited thereto. In embodiments of the presentinvention, the first conductive semiconductor layer 110, the activelayer 120, and the second conductive semiconductor layer 130 may bereferred to as a light emitting structure.

Next, a second electrode layer 140 can be formed over the secondconductive semiconductor layer 130. The second electrode layer 140 mayinclude a second ohmic layer 142, a reflective layer, a coupling layerand a second substrate 144. For example, when the second electrode layer140 includes the second ohmic layer 142, the second ohmic layer 142 canbe formed by laminating single metal (or a metal alloy) and metal oxidein a multi-layer such that hole injection can be efficiently performed.For example, the second ohmic layer 142 may include at least oneselected from the group consisting of ITO, IZO (In—ZnO), GZO (Ga—ZnO),AZO (Al—ZnO), AGZO (Al—Ga ZnO), IGZO (In—Ga ZnO), IrOx, RuOx, RuOx/ITO,Ni/IrOx/Au and Ni/IrOx/Au/ITO. However, the present invention is notlimited thereto.

Further, when the second electrode layer 140 includes the reflectivelayer, the reflective layer may include a metal layer including Al, Ag,or an alloy of Al and Ag. The Al or Ag effectively reflects the lightgenerated from the active layer 120 to significantly improve lightextraction efficiency of the LED. When the second electrode layer 140includes the coupling layer, the reflective layer may serve as thecoupling layer. Further, the coupling layer may be formed using Ni, Auand the like.

Further, the second electrode layer 140 may include the second substrate144. If the first conductive semiconductor layer 110 has a sufficientthickness of about 50 μm or more, a process for forming the secondsubstrate 144 may be omitted. For example, the second substrate 144 mayinclude metal (e.g. Cu) having superior electrical conductivity, a metalalloy (e.g. Cu alloy) or conductive semiconductor materials (e.g. Si, Moand SiGe) such that the hole injection can be efficiently performed. Thesecond substrate 144 can be formed using an electrochemical metaldeposition method or a bonding method using eutectic metal.

Then, as shown in FIG. 3, the first substrate 100 can be removed suchthat the first conductive semiconductor layer 110 is exposed. The firstsubstrate 100 can be removed using high power laser or a chemicaletching method. Further, the first substrate 100 can also be removedthrough physical polishing.

Thereafter, the roughness R can be formed on a part of the firstconductive semiconductor layer 110. For example, a first pattern 310 isformed on the first conductive semiconductor layer 110. Subsequently,the part of the first conductive semiconductor layer 110 is etched byusing the first pattern 310 as an etch mask to form the roughness R.Accordingly, the roughness R is formed.

For example, the first pattern 310 may include dielectric material suchas silicon oxide or silicon nitride, and may have a thickness of about0.5 μm to about 2 μm. However, the present invention is not limitedthereto. The first pattern 310 may vary depending on a structure of theLED to be manufactured.

The first pattern 310 can be formed on an area in which a firstelectrode layer 150 is to be formed. Then, as shown in FIG. 3, theroughness R can be formed on the exposed first conductive semiconductorlayer 110 by using the first pattern 310 as the etch mask. The roughnessR is formed on the exposed first conductive semiconductor layer 110 toimprove the light extraction efficiency of the LED. The surface of theexposed first conductive semiconductor layer 110 represents nitrogenpolarization, so the roughness R can be formed through wet etching usinga KOH solution. The roughness R can also be formed through dry etching.

FIG. 4 shows another example of forming the roughness R on the part ofthe first conductive semiconductor layer. Material constituting thefirst pattern 310 may remain in an area having no roughness R and asecond pattern 320 having holes may exist in the remaining area.

For example, the hole of the second pattern 320 may have a photoniccrystalline structure like a cylinder. However, the present invention isnot limited thereto. For example, when the hole of the second pattern320 has a cylindrical shape, the hole may have a diameter of about 3 μm,and the distance between the holes may be about 2 μm. Then, as shown inFIG. 4, the roughness R can be formed on the exposed first conductivesemiconductor layer 110 by using the second pattern 320 as the etchmask. For example, the first conductive semiconductor layer 110, whichis exposed through the holes, may be dry-etched with a depth of about0.5 μm through reactive ion etching (RIE).

Thereafter, the portion 115 having an implanted element is formed in thefirst conductive semiconductor layer 110 having the roughness R by usingthe first pattern 310 as the etch mask. The portion 115 having animplanted element may be formed before the roughness R is formed.

For example, the implanted elements may be any element. In an embodimentof the present invention, the implanted elements are rare earth elementsthat are implanted into the surface of the exposed first conductivesemiconductor layer 110 having the roughness R. The rare earth elementsmay include Er, Eu, Pr, Tb, Dy, Ce, Sm, Gd, Ho, Yb, Lu, Nd, Pm, Tm andthe like. The rare earth elements can be selected according to thewavelength of the light emitted from the active layer (light emittinglayer). At least one kind of the rare earth elements can be implanted.The implantation amount of the rare earth elements may vary depending onproperties of the white light of the LED. The rare earth elements can beimplanted through ion implantation.

For example, Er (green) and Eu (red), which are rare earth elements, maybe implanted into the surface of the exposed first conductivesemiconductor layer 110 having the roughness R through the ionimplantation at the temperature of about 200° C. to about 900° C.However, the present invention is not limited thereto.

Meanwhile, referring to FIG. 4, after the second pattern 320 is removedand a third pattern is formed on an area having no roughness R, the rareearth element implantation layer 115 may be formed by using the thirdpattern as an ion implantation mask. Then, the third pattern is removedto form the first electric layer 150.

Hereinafter, properties of the rare earth element implanted according tothe embodiment will be described. In the rare earth element,4f-electrons, which are partially filled in the rare earth element, areexcited by external excitation light, and then the excited electronsreturn to a stable state through inner transition, so each rare earthelement emits light having specific energy. Such rare earth elements mayinclude Er, Eu, Pr, Tb, Dy, Ce, Sm, Gd, Ho, Yb, Lu, Nd, Pm, Tm and thelike. Similarly to the rare earth elements, transition metal elementscan emit light of specific energy. Accordingly, the implanted elementmay be one or more of the transition metal elements.

The rare earth elements, for example, can effectively emit light whenthe rare earth elements are doped in a crystal lattice serving as a hostmatrix and exist as a cation while occupying a cation site of the hostmatrix. Semiconductor host matrices including a nitride semiconductormay serve as a host matrix through which the rare earth elements caneffectively emit light. The rare earth elements exist in the host matrixas the cation with an oxidation number of +2, +3 or +4. The electrons,which are partially filled in the 4f electron shell, are surrounded by5s and 5p electron shells completely filled with electrons, so theelectrons in the 4f electron shell are not significantly affected by acrystal field due to a shielding effect of outer shell electrons.

When intra-f optical transition of the rare earth ions occurs, lightwithin the range of a visible ray can be emitted at the normaltemperature. Ultraviolet light UV or light generated from a blue nitridesemiconductor LED can be used for the excitation light.

The 4f electrons of the rare earth ions can perform f-f transitionforbidden by parity selection rules and f-d transition permitted by theparity selection rules. For example, the f-f transition is observed inTb³⁺ (green), Sm³⁺ (red), Tm³⁺ (blue) and the like, and light emissionthrough the f-d transition is observed in Eu³⁺ (red), Ce³⁺ (blue) andthe like. Further, 5d electrons exist in the outermost shell, so the 5delectrons are easily affected by the crystal field and stronglydependent on the host matrix material.

In the case of Eu³⁺ ions in a GaN host matrix, when electrons excited bythe external excitation light perform inner shell transition, red lighthaving a wavelength of 622 nm is emitted. Further, Tb³⁺ ions can emitgreen light having a wavelength of 545 nm, Er³⁺ ions can emit greenlight having a wavelength of 537 nm, Pr³⁺ ions can emit red light havingwavelengths of 645 nm and 652, and Tm³⁺ ions can emit blue light havinga wavelength of 450 nm.

For example, if ultraviolet (UV) light is irradiated onto the GaN thinfilm containing the rare earth elements such as Tm, Er and Eu, the rareearth elements emit blue, green and red lights, so white light can beemitted. If blue excitation light is irradiated onto the GaN thin filmcontaining the rare earth elements such as Er and Eu, the rare earthelements absorb a part of the blue light to emit green and red lights,so white light can be emitted.

Next, as shown in FIG. 5, the first electrode layer 150 is formed on anarea of the conductive semiconductor layer 110, where the rare earthelement implantation layer 115 is not formed. For example, the firstpattern 310 is removed and the first electrode layer 150 is formed onthe exposed conductive semiconductor layer 110. The first electrodelayer 150 may include a first ohmic layer, a reflective layer, a firstelectrode and the like. For example, when the electrode layer 150includes the reflective layer, the reflective layer may include a metallayer containing Al, Ag, or an alloy of Al and Ag.

Further, when the electrode layer 150 includes the first ohmic layer,the first ohmic layer includes at least one selected from the groupconsisting of ITO, IZO (In—ZnO), GZO (Ga—ZnO), AZO (Al—ZnO), AGZO (Al—GaZnO), IGZO (In—Ga ZnO), IrOx, RuOx, RuOx/ITO, Ni/IrOx/Au andNi/IrOx/Au/ITO. However, the present invention is not limited thereto.If the first ohmic layer is a transparent layer, since the emitted lightcan pass through the first ohmic layer, the reflective layer may beomitted.

According to the embodiment, the first electrode layer is formed on thehigh-quality N type nitride semiconductor layer, which has no rare earthelements and has superior electrical conductivity, so that theelectrical properties of the LED can be improved. Then, a firstelectrode can be formed on the first ohmic layer.

According to the LED of the embodiment, the rare earth elements arepartially implanted into the surface of the first conductivesemiconductor layer and the first electrode layer is formed on the firsthigh-quality conductive semiconductor layer, so degradation incrystallization of a thin film caused by the implantation of the rareearth elements can be prevented, and degradation in performance of theLED caused by degradation of electrical properties can be effectivelysolved, so that a single chip white LED having high performance can beachieved.

Further, the LED of the embodiment does not use the conventionalfluorescent substance, so problems caused by the use of the fluorescentsubstance can be reduced or prevented and industrial application fieldsof the nitride semiconductor LED can be considerably diversified.

Second Embodiment

FIG. 6 is a sectional view showing an LED according to a secondembodiment of the present invention. The LED according to the secondembodiment can include a conductive substrate 200 a, a first conductivesemiconductor layer 210 formed on the conductive substrate 200 a, anactive layer 220 and a second conductive semiconductor layer 230.Roughness R is formed at a part of the conductive substrate 200 a, andan implanted element 215 is implanted in the conductive substrate 200 ahaving the roughness R.

According to the second embodiment, the implanted element 215 can bepartially implanted into the surface of the conductive substrate 220 aand the first electrode layer 150 is formed on the conductive substrate220 a of high-quality, so degradation in crystallization of a thin filmcaused by the implantation of the rare earth elements can be reduced orprevented, degradation in performance of the LED caused by degradationof electrical properties can be effectively reduced or solved, and asingle chip white LED having high performance can be achieved.

According to the second embodiment, the conductive substrate can beemployed, the roughness can be formed on a part of the conductivesubstrate, and the implanted element can be implanted.

Hereinafter, the manufacturing method of the LED according to anotherembodiment of the present invention will be described with reference toFIGS. 6 to 8, with a focus on differences relative to that of the firstembodiment. The second embodiment can adopt the technicalcharacteristics of the first embodiment.

First, as shown in FIG. 7, the conductive substrate 200 a can beprepared. The conductive substrate 200 a has superior electricalconductivity and is transparent within the range of a visible ray. Theconductive substrate 200 a may include a single crystal substrate or amulticrystalline substrate containing GaN, gallium oxide Ga₂O₃, zincoxide ZnO, silicon carbide SiC, metal oxide and the like.

Next, similarly to the first embodiment, the first conductivesemiconductor layer 210, the active layer 220, the second conductivesemiconductor layer 230 and a second electrode layer 240 can be formedon the conductive substrate 200 a. The second electrode layer 240 mayinclude a second ohmic layer, a reflective layer and the like.

Then, a lower portion of the conductive substrate 200 a (which is anupper portion of the conductive substrate 200 a when viewed in FIG. 8)can be partially removed. For example, a polishing process is performedwith respect to the lower surface of the conductive substrate 200 a.Thickness of the conductive substrate 200 a, which is thinned throughthe polishing process, may vary depending on products to which thesemiconductor device is employed. For example, the conductive substrate200 a having a thickness of about 400 μm to about 500 μm can be subjectto the polishing process, such that the conductive substrate 200 a mayhave a thickness of about 70 μm to about 100 μm. However, the presentinvention is not limited thereto.

If a nitride semiconductor thin film is formed on the conductivesubstrate 200 a through thin film growth equipment at the hightemperature, the crystallization state of the lower surface of theconductive substrate 200 a may be degraded due to high thin film growthtemperature and reaction gases. In this regard, the electricalproperties of the LED can be improved if the lower surface of theconductive substrate 200 a is polished.

Thereafter, the roughness R can be formed on a part of the conductivesubstrate 200 a, and the rare earth elements can be implanted into theconductive substrate 200 a having the roughness R to form the rare earthelement implantation layer 215. For example, a fourth pattern having apredetermined shape is formed on the high-quality conductive substrate200 a, which is exposed in a state in which the lower portion of theconductive substrate 200 a is removed, the conductive substrate 200 a isetched by using the fourth pattern as an etch mask, and then the rareearth elements are implanted by using the fourth pattern as an ionimplantation mask. However, the present invention is not limitedthereto.

Further, a layer of implanted elements 215, which may include one ormore rare earth elements may be formed before the roughness R is formedon the part of the conductive substrate 200 a.

According to the second embodiment, the rare earth elements can bepartially implanted into the surface of the conductive substrate and thefirst electrode layer is formed on the high-quality conductivesubstrate, so degradation in crystallization of a thin film caused bythe implantation of the rare earth elements can be reduced or prevented,degradation in performance of the LED caused by degradation ofelectrical properties can be effectively reduced or solved, and a singlechip white LED having high performance can be achieved.

Then, the fourth pattern can be removed and the first electrode 250 canbe formed on a predetermined area of the conductive substrate 200 a,which has no roughness R. The first electrode 250 may include a firstohmic layer, a reflective layer, a first electrode and the like.

According to the second embodiment, the first electrode layer 250 isformed on the high-quality conductive substrate 200 a, which has no rareearth elements and has superior electrical conductivity, so that theelectrical properties of the LED can be improved.

According to the second embodiment, the rare earth elements can bepartially implanted into the surface of the conductive substrate and thefirst electrode layer is formed on the high-quality conductivesubstrate, so degradation in crystallization of a thin film caused bythe implantation of the rare earth elements can be reduce or prevented,degradation in performance of the LED caused by degradation ofelectrical properties can be effectively reduced or solved, and a singlechip white LED having high performance can be achieved.

FIG. 9 is a sectional view showing an LED according to a thirdembodiment of the present invention. In discussing this embodiment, onlydifferences with the first embodiment, for example, will be discussedfor clarity and to avoid redundancy. Specifically, the LED includes anundoped semiconductor layer 105 formed on the first conductivesemiconductor layer 110. A portion 115 having an implanted element is inthe undoped semiconductor layer 105 having the roughness R. A firstelectrode layer 150 is formed on the first conductive semiconductorlayer 110 within a cavity 101. In embodiments of the present invention,the undoped semiconductor layer 105, the first conductive semiconductorlayer 110, the active layer 120, the second conductive semiconductorlayer 130 may be referred to as a light emitting structure. Also, theundoped semiconductor layer 105 refers to a semiconductor layer that isnot intentionally doped to be a conductive semiconductor, but maycontain small amount of impurity is included unintentionally.

Further, the LED of the embodiments of the present invention do not usethe conventional fluorescent substance, so problems caused by the use ofthe fluorescent substance can be reduced or prevented and industrialapplication fields of the nitride semiconductor LED can be considerablydiversified.

In embodiments of the present invention, the roughness R is a portionhaving a textured surface roughness. Such textured surface roughness maybe at least one protrusion and/or at least one depression. The texturedsurface roughness may be a plurality of protrusions and depressionsformed on a surface, or a portion thereof, and may have regular orirregular periodicity, or may be formed randomly. The shapes of theprotrusions may be spine-like, column-like, or other shapes, and theshapes of the depressions may be indentations, channels, grooves, orother shapes.

In embodiments of the present invention, the implanted element may beany element that have fluorescence or are able to absorb one light togenerate another light. In a broad sense, an element refers to anyelement listed in the periodic table. It should be understood that lightalso references any radiation, as well as wavelength bands of light thatare not visible to humans.

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the disclosure. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the invention, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A light emitting device, comprising: a lightemitting structure comprising an active layer to generate first light, afirst conductive semiconductor layer on the active layer, and a secondconductive semiconductor layer on the active layer so that the activelayer is disposed between the first and second conductive semiconductorlayers; and a first electrode layer on a first portion of a top surfaceof the light emitting structure, wherein a portion of the light emittingstructure comprises a rare earth element implantation layer beingimplanted with at least one element which generates second light fromthe first light, and wherein the rare earth element implantation layeris in a second portion of the top surface of the light emittingstructure.
 2. The light emitting device as claimed in claim 1, whereinthe at least one element is implanted in the first conductivesemiconductor layer.
 3. The light emitting device as claimed in claim 1,wherein the light emitting structure further comprises an undopedsemiconductor layer, and the at least one element is implanted in theundoped semiconductor layer.
 4. The light emitting device as claimed inclaim 1, wherein the at least one element includes rare earth elementcomprising at least one selected from the group consisting of Er, Eu,Pr, Tb, Dy, Ce, Sm, Gd, Ho, Yb, Lu, Nd, Pm and Tm.
 5. The light emittingdevice as claimed in claim 1, wherein the first electrode layercomprises: a reflective layer on the first conductive semiconductorlayer; and a first electrode on the reflective layer.
 6. The lightemitting device as claimed in claim 1, further comprising a secondelectrode layer on the second conductive semiconductor layer.
 7. Thelight emitting device as claimed in claim 6, wherein the secondelectrode layer comprises at least one of an ohmic layer, a reflectivelayer, a coupling layer and a substrate.
 8. The light emitting device asclaimed in claim 7, wherein the light emitting structure comprises atextured surface roughness.
 9. The light emitting device as claimed inclaim 8, wherein the at least one element is formed in the texturedsurface roughness of the light emitting structure.
 10. The lightemitting device as claimed in claim 1, further comprising a conductivesubstrate on the first conductive semiconductor layer, wherein a portionof the conductive substrate is implanted with the at least one elementwhich generates the second light from the first light.
 11. The lightemitting device as claimed in claim 10, wherein the conductive substratecomprises a single crystal substrate or a multicrystalline substratewhich includes at least one selected from the group consisting ofgallium nitride, gallium oxide, zinc oxide, silicon carbide and metaloxide.
 12. The light emitting device as claimed in claim 10, furthercomprising a textured surface roughness formed on a portion of theconductive substrate.
 13. The light emitting device as claimed in claim12, wherein the at least one element is implanted in the conductivesubstrate including the textured surface roughness.
 14. The lightemitting device as claimed in claim 10, wherein the first electrodelayer is on an area of the conductive substrate, where the at least oneelement is not implanted.
 15. The light emitting device as claimed inclaim 14, wherein the first electrode layer comprises: a reflectivelayer on the first conductive semiconductor layer; and a first electrodeon the reflective layer, wherein the reflective layer comprises an ohmiclayer.
 16. The light emitting device as claimed in claim 10, furthercomprising a second electrode layer on the second conductivesemiconductor layer.
 17. The light emitting device as claimed in claim16, wherein the second electrode layer comprises at least one of anohmic layer, a reflective layer, a coupling layer and a substrate. 18.The light emitting device as claimed in claim 1, wherein a top surfacelevel of the rare earth element implantation layer is substantially thesame as a bottom surface level of the first electrode layer.
 19. Thelight emitting device as claimed in claim 1, wherein the first electrodelayer does not vertically overlap with the rare earth elementimplantation layer.
 20. A light emitting device, comprising: a lightemitting structure comprising an n-type conductive semiconductor layer,a p-type conductive semiconductor layer, and an active layer disposedbetween the n-type and the p-type conductive semiconductor layers,wherein the active layer generates first light; a first electrode layeron a first portion of a top surface of the light emitting structure; anda second electrode layer under the light emitting structure; wherein aportion of the light emitting structure comprises a rare earth elementlayer having at least one material which generates second light from thefirst light, wherein the rare earth element layer is in a second portionof the top surface of the light emitting structure, wherein the secondelectrode layer comprises a reflective layer, a coupling layer and asubstrate, and wherein the coupling layer is disposed between thereflective layer and the substrate.